The geometric sequence $(a_i)$ is defined by the formula: $a_i = \dfrac{1}{3} \left(-3\right)^{i - 1}$ What is $a_{2}$, the second term in the sequence?
Solution: From the given formula, we can see that the first term of the sequence is $\dfrac{1}{3}$ and the common ratio is $-3$ The second term is simply the first term times the common ratio. Therefore, the second term is equal to $a_2 = \dfrac{1}{3} \cdot -3 = -1$.